Quarter	Billions of US Dollars
1987-01-01	3.434
1987-04-01	3.841
1987-07-01	4.120
1987-10-01	4.250
1988-01-01	4.666
1988-04-01	4.999
1988-07-01	5.256
1988-10-01	5.850
1989-01-01	5.494
1989-04-01	5.723
1989-07-01	5.666
1989-10-01	6.302
1990-01-01	6.888
1990-04-01	7.393
1990-07-01	8.146
1990-10-01	8.364
1991-01-01	9.470
1991-04-01	9.567
1991-07-01	9.895
1991-10-01	11.969
1992-01-01	12.018
1992-04-01	12.506
1992-07-01	12.729
1992-10-01	11.761
1993-01-01	8.889
1993-04-01	7.926
1993-07-01	8.009
1993-10-01	8.648
1994-01-01	8.486
1994-04-01	8.684
1994-07-01	8.896
1994-10-01	8.007
1995-01-01	6.967
1995-04-01	7.007
1995-07-01	6.918
1995-10-01	7.557
1996-01-01	6.928
1996-04-01	6.837
1996-07-01	6.663
1996-10-01	7.197
1997-01-01	6.555
1997-04-01	7.286
1997-07-01	7.370
1997-10-01	7.036
1998-01-01	6.539
1998-04-01	8.379
1998-07-01	9.579
1998-10-01	10.518
1999-01-01	11.055
1999-04-01	15.632
1999-07-01	16.771
1999-10-01	19.838
2000-01-01	23.293
2000-04-01	27.674
2000-07-01	28.886
2000-10-01	34.403
2001-01-01	33.140
2001-04-01	34.674
2001-07-01	39.812
2001-10-01	39.499
2002-01-01	39.486
2002-04-01	47.146
2002-07-01	48.188
2002-10-01	51.375
2003-01-01	53.682
2003-04-01	59.414
2003-07-01	60.900
2003-10-01	72.350
2004-01-01	77.069
2004-04-01	84.708
2004-07-01	99.026
2004-10-01	123.924
2005-01-01	140.246
2005-04-01	144.267
2005-07-01	134.749
2005-10-01	152.691
2006-01-01	177.804
2006-04-01	198.976
2006-07-01	217.007
2006-10-01	248.561
2007-01-01	273.614
2007-04-01	299.124
2007-07-01	314.181
2007-10-01	333.471
2008-01-01	379.145
2008-04-01	408.784
2008-07-01	372.063
2008-10-01	380.866
2009-01-01	375.345
2009-04-01	406.799
2009-07-01	422.807
2009-10-01	424.666
2010-01-01	391.347
2010-04-01	351.098
2010-07-01	408.994
2010-10-01	401.866
2011-01-01	447.231
2011-04-01	463.341
2011-07-01	442.630
2011-10-01	422.707
2012-01-01	428.148
2012-04-01	388.302
2012-07-01	397.903
2012-10-01	399.507
2013-01-01	370.742
2013-04-01	378.052
2013-07-01	392.640
2013-10-01	399.288
2014-01-01	385.506
2014-04-01	375.053
2014-07-01	328.544
2014-10-01	316.023
2015-01-01	281.726
2015-04-01	286.701